X pipe H pipe or side by side

[Phreakish]

I agree with all this except that all street cars run full length exhaust. I have not run a full exhaust on my street toys since 1981.

If you are not required by law I see no use for it.

Agreed - and nothing against it but I value my hearing too much. The small gain in performance isn't worth my going (more) deaf ;)

I was speaking more generally in that constraints for a street car typically include some sort of exhaust system.

 

[Phreakish]

The part that is getting lost here also is what RPM range do you use most? All these NASCAR and open header examples don't really mean squat for guys wanting street performance. Street or all out drag only it still depends on what you have. I run 452 CID through fenderwell Hooker competition series headers with 18" 3.5" collectors. Those in turn connect to 3" pipe with an X and 3" in and out flow masters that turn down at the axle. Advantage exhaust on the 1/8th mile with the exception of the fact it marginalizes my poor suspension.

The problem is the generalizations.

Those who see no need for cross-overs are of the opinion that nothing will beat their properly tuned header extensions - and they're probably right in most cases.

Those who run them do so because they aren't able or willing to run dumped headers.

Those that claim it's ONLY snake-oil, or ONLY helps a marginal system, or ONLY exists to make things quieter aren't quite on-target because there ARE systems that will benefit even with a perfectly setup (full) exhaust system but it does also make things quieter by default.

Again, application dependent and not a drawback unless the builder is looking for maximum sound.

Someone willing to run open headers probably isn't in the market for a cross over since they're not looking for quiet

 

[pishta]

I ran my mazda for about 3 minutes without a headpipe, straight cast 4 into 2 "double barrel" manifold and I could barely get the thing rolling with a stick, NO torque. After I put the full exhaust back on, back to normal stump puller. I did the same with a 318, no manifolds...no restriction, right? Na, didnt run at all. Could have burned the exhaust valves too. I remember seeing a Pontiac gasser with open headers out the front wheel wells and a long a$$ H pipe not 3 inches before the dumps tying both sides together. Looked like a 2nd straight axle.

 

[ir3333]

I just dunno how many more times I can explain it to you without you getting it? What about it are you not quite understanding ir3333?

Oh My!
i understand how equal length headers tuned for a specific engine will keep
each bank of 4 identical cylinders effectively scavenged and maximize power.
...and i understand that you think joining them will make even more power!

 

[MoparLeo]

Here is another example, the 180 degree header. Each tube is attached to the next cylinder in the firing order. This maximizes the scavenging affect. But these are expensive and sometimes there is not room in the engine compartment to do this. They are popular on boats and racecars because there is plenty of room. Picture the exhaust on an open wheel racecar. Always tubes tuned to the next in the firing order = more power. Tube length and tube diameter affect horsepower/torque peak. The tri-y with steps in the tube diameter accomplish the same thing. We use to adjust the collector length with a yellow crayon. Draw a line along the length of the collector, run the engine and look at where the crayon line stopped melting.

 

[mguner]

Using and H or X has never been about quiet for me. I found improvement on everything. It is cheap power for most cars running an exhaust system. And for guys that can't buy all the parts they want when they want, already have parts on hand they want to use, did't design the thing on a CAD system or bought a car already built that needs a little extra something DO IT!

 

[yellow rose]

Using and H or X has never been about quiet for me. I found improvement on everything. It is cheap power for most cars running an exhaust system. And for guys that can't buy all the parts they want when they want, already have parts on hand they want to use, did't design the thing on a CAD system or bought a car already built that needs a little extra something DO IT!

If your exhaust is as you say, I would tell you to rethink your exhaust port and exhaust lobe. You exhaust is close enough that the h pipe should be a loss.

Or you don't have enough converter.

 

[mguner]

452 heads with pocket port and gasket match. 284/484 hyd cam with 1.75 rockers, 3500 TCI converter.

 

[Lustle]

Oh My!
i understand how equal length headers tuned for a specific engine will keep
each bank of 4 identical cylinders effectively scavenged and maximize power.
...and i understand that you think joining them will make even more power!

I don't think it. I know it. Because it's proven. Over and over again. By many different people, race teams, performance shops, etc. Using the opposite bank of cylinder's to promote and increase the scavenging effect is well documented. And it has been explained here how it works several times.

If you'd like to tell me what part you aren't getting, I will honestly try to explain it for you. I can get as technical as you like if it will help you understand. But I honestly think you aren't actually interested in learning about it, cause you've refused to listen to or understand all the explaining we've done here.

 

[Lelo Dart]

I love these threads. IMO the X pipe can only help with full exhaust. My 2 cents. Carry on.

 

[67dartgtgo]

I asked my exhaust guy, a verrry knowledgable custom exhaust manufacturer and racer, both circle track and strip and this is what he said. The difference between "X" and "H" pipes is where you intend to use them. "X" pipes are more for circle track racing because they scavenge better at higher rpm. "H" pipes scavenge better in lower rpm ranges where torque is more appealing like when launching at the strip. I had him put an "H" in mine.

 

[Wire]

If you hold your hand behind a tailpipe, the exhaust flow feels like a continuous stream, but it's actually a series of pulses, each of which is created every time one cylinder's exhaust valve opens in the firing order. On a typical V8 engine, one cylinder on each bank fires within 90 degrees of crankshaft rotation of another cylinder on the same bank. The resulting exhaust pulses are very close together as they travel through the exhaust system and on some vehicles they create a popping noise. H-pipe sections were first installed to quiet this exhaust noise. When the two close firing cylinders are exhausting on one bank, there is nothing happening in the other bank, so connecting both pipes effectively enlarged the exhaust system, allowing these exhaust pulses to exit through both sides of the system. It was found that, with the addition of an H-pipe, exhaust noise could be reduced by as much as 2 decibels. Adding an H-pipe section also increases power. Even when headers are installed, these close firing cylinders are competing for space in the exhaust pipe after the collector, which creates backpressure and reduces power. Connecting the exhaust pipes allows pressure to escape to the other side of the system, with a resulting gain in low-end and mid-range torque. However, the effectiveness of an H-pipe section decreases somewhat at higher rpm. The increased exhaust gas velocity at high rpm causes most of the exhaust to take the path of least resistance and continue down the exhaust pipe, rather than make the turn into the H-pipe. The solution to this problem is the X-pipe. With an X-pipe section, the two sides of the exhaust system are merged rather than just connected, allowing the exhaust from each bank to easily flow into both exhaust pipes. The exhaust pressure on both banks is equalized and power is increased at all engine speeds.

 

[yellow rose]

If you hold your hand behind a tailpipe, the exhaust flow feels like a continuous stream, but it's actually a series of pulses, each of which is created every time one cylinder's exhaust valve opens in the firing order. On a typical V8 engine, one cylinder on each bank fires within 90 degrees of crankshaft rotation of another cylinder on the same bank. The resulting exhaust pulses are very close together as they travel through the exhaust system and on some vehicles they create a popping noise. H-pipe sections were first installed to quiet this exhaust noise. When the two close firing cylinders are exhausting on one bank, there is nothing happening in the other bank, so connecting both pipes effectively enlarged the exhaust system, allowing these exhaust pulses to exit through both sides of the system. It was found that, with the addition of an H-pipe, exhaust noise could be reduced by as much as 2 decibels. Adding an H-pipe section also increases power. Even when headers are installed, these close firing cylinders are competing for space in the exhaust pipe after the collector, which creates backpressure and reduces power. Connecting the exhaust pipes allows pressure to escape to the other side of the system, with a resulting gain in low-end and mid-range torque. However, the effectiveness of an H-pipe section decreases somewhat at higher rpm. The increased exhaust gas velocity at high rpm causes most of the exhaust to take the path of least resistance and continue down the exhaust pipe, rather than make the turn into the H-pipe. The solution to this problem is the X-pipe. With an X-pipe section, the two sides of the exhaust system are merged rather than just connected, allowing the exhaust from each bank to easily flow into both exhaust pipes. The exhaust pressure on both banks is equalized and power is increased at all engine speeds.

All of this is correct.


Where I disagree is in that these pipes ALWAYS make power. In most cases, they do not. If you are working with w big budget, and can use multiple cams and have days on the dyno, you may find bit of power in certain circumstances. Usually in very narrow RPM ranges. Then, to verify those results, you need to get on the chassis dyno and flog it to death to verify the engine dyno results. After all that, you go to the track and see if those numbers verify your research.


I called a very well know muffler manufacturer way back in the early 1980's. I was required to use a muffler on my race car. I told him my HP and RPM and then I said I don't want to lose ANY HP. And if that can't be done, I want to minimize my losses.

After 20 minutes of discussion, we actually picked a muffler. I was using an early A body so space was at a premium. Then he dropped the other shoe. The only was to insure a minimal loss with the muffler, was to run a crossover pipe. I told him my results with testing on those things and he laughed. He said that most of the X and H pipes were for noise only. They don't work. To make a LONG story a bit shorter, he told me the crossover pipe MUST be the same diameter as the collector (I was using a 4 inch collector) and that the length can be no LESS than 4 TIMES the diameter in length!!!!!!!!!!!!!!!!!!!!!!!

Then he said that is why you don't see drag cars with crossovers. To actually make them work it is almost impossible to make them fit. So I said the PS and Comp guys KNOW they are giving up power and they let it go? He said no, they could possibly find HP with a crossover, but when the cam/exhaust lobe/ exhaust port is correct and you are not required to run a muffler there in no gain.

So again, it depends on application and how well you have ironed out the above systems.

 

[Doosterfy]

I went w/ 3.5" dual turn downs ( no room to go over the dana w/ the stock gas tank), I doubt very seriously that h, or x pipe would show enough, "if any" improvement at over 600h.p. probly not worth their weight !

I disagree with you on that Bob. NASCAR Cup cars all have X pipe, they have for years now. If it did not add power and/or torque they would not be using them. Non restrictor plate Cup engines have over 850 hp.

 

[Doosterfy]

Ok when YOU test and do R&D like nascar then I would agree. I can't tell you how many times on the dyno I have taken both styles off and made power. And at the tack.

If, and it is a big IF, you are testing cam/cylinder head/induction/exhaust then you MIGHT find power in a very narrow rpm.

I am not the only guy out there testing this stuff, and finding 99% of the results outright lies. Joe Sherman, a very well respected engine builder who worked with Edelbrock has been dyno testing this stuff way before I started. Our results, REAL WORLD RESULTS agree.

Go join speedtalk.com and then search the site for x and h pipe threads. And you will see the guys who love x and h pipes and tri-y headers and merge collectors (another joke for 99.95% of us) are the same ones who get to spend 100k in development with the latest testing equipment you can buy. All in a computer controlled atmosphere, both the dyno room and flow bench room.


Do the research before you spend your money. You can spend less money and get more than to mess with that stuff.

But some guys are slow learners, or have handicapped combinations. I suggest fixing the combo and then be prepared to spend big $$$$$$$ to do and get reliable testing.


Flame on.

I see what you're saying and can't make an argument against it because I don't have the time, money and resources to do all the testing you have apparently done. With that said can we not assume that most guys on here are hobby guys like me and lack the resources to completely science out the headers on their cars like you have done? I can say this however, every car I've had with a full exhaust gained torque and sounded better when I added an H pipe. The cost was minimal and all it took was a few hours of work. Maybe it is a crutch but its a nice inexpensive one that works good.

 

[yellow rose]

I see what you're saying and can't make an argument against it because I don't have the time, money and resources to do all the testing you have apparently done. With that said can we not assume that most guys on here are hobby guys like me and lack the resources to completely science out the headers on their cars like you have done? I can say this however, every car I've had with a full exhaust gained torque and sounded better when I added an H pipe. The cost was minimal and all it took was a few hours of work. Maybe it is a crutch but its a nice inexpensive one that works good.

Did you actually DYNO your stuff? If not, you can't say what happened.

I always relate this story. I had a customer come in and want an engine. I told him to bring it what he had, so I could get it on the pump to see what he truly had for HP (and as per normal, he mas 150 less that he thought as he had an HONEST 350 and not 500).

We made wholesale changes to his program, made him correct his gearing and buy new headers. When done, we found about 75 HONEST horsepower. And he promised me he was a chassis tuning wizard.

At the track his car was S-L-O-W. After 3 weeks of pissing and moaning I decided to go out and see what the issue was. He couldn't tune a fish. I wasn't any help, be cause I'm a drag race guy. He blew the tires off every time he touched the throttle. Since he couldn't fix his car, I took 86 degrees total timing out and made the throttle open only about 75%. Then he set his fastest lap times every.

There is more to testing and tuning than time slips. Sometimes, killing horsepower is faster. And without actual data, you have no real idea if you made HP, lost HP, moved the torque curve up (making the same RPM effectively less powerful), moved the torque curve down (same as killing HP).

I'm not criticizing you. Just saying without data, you have no idea what happened, except the car was quieter and went faster.

I hope you understand this.

 

[Oldmanmopar]

H pipe is more power and less money then a X pipe. below is a dyno sheet from someone that doesn't sell X pipes. Those who have them will never admit they waisted their money.

Think of it this way Have two hoppers hook up to an X. Flush them both at the same time and the **** will slam into each other.

Most will tell you the pulsation from side to side helps flow. Old school mopar firing order is 1, / 8,4, / 3, / 6,/ 5,7, / 2 this is the pulse not so effective is it.

H-PIPE all the way for old school mopar V-8's.

 

[yellow rose]

H pipe is more power and less money then a X pipe. below is a dyno sheet from someone that doesn't sell X pipes. Those who have them will never admit they waisted their money.

Think of it this way Have two hoppers hook up to an X. Flush them both at the same time and the **** will slam into each other.

Most will tell you the pulsation from side to side helps flow. Old school mopar firing order is 1, / 8,4, / 3, / 6,/ 5,7, / 2 this is the pulse not so effective is it.

H-PIPE all the way for old school mopar V-8's.

Where is the dyno sheet with a quality header and correctly sized exhaust and correctly chosen cam?

I can look at those two dyno pulls and tell you for a FACT there is less than .005 in the time slips between the two systems.

I'd bet you what you want if I spec'd the cam and exhaust, the H and X pipe would show SIGNIFICANT losses. They always do when things are correct.





Unless you are running a restrictor plate engine at 8000 RPM. Or you can flat foot it around Daytona or Talladega.

 

[Doosterfy]

Did you actually DYNO your stuff? If not, you can't say what happened.

I always relate this story. I had a customer come in and want an engine. I told him to bring it what he had, so I could get it on the pump to see what he truly had for HP (and as per normal, he mas 150 less that he thought as he had an HONEST 350 and not 500).

We made wholesale changes to his program, made him correct his gearing and buy new headers. When done, we found about 75 HONEST horsepower. And he promised me he was a chassis tuning wizard.

At the track his car was S-L-O-W. After 3 weeks of pissing and moaning I decided to go out and see what the issue was. He couldn't tune a fish. I wasn't any help, be cause I'm a drag race guy. He blew the tires off every time he touched the throttle. Since he couldn't fix his car, I took 86 degrees total timing out and made the throttle open only about 75%. Then he set his fastest lap times every.

There is more to testing and tuning than time slips. Sometimes, killing horsepower is faster. And without actual data, you have no real idea if you made HP, lost HP, moved the torque curve up (making the same RPM effectively less powerful), moved the torque curve down (same as killing HP).

I'm not criticizing you. Just saying without data, you have no idea what happened, except the car was quieter and went faster.

I hope you understand this.

I have never used a dyno of any kind. I go by time slips. Sure there may be more to tuning than time slips but its tough to say something does not work when the ET gets lower and the MPH goes up on the time slips. That's not to say that what you are saying is not true, I'd say my combos are likely not as thorough or completely scienced out as what you build. That goes right back to what I said in my previous reply, it may be a crutch but on most home built cars it works. Are you a pro engine builder/tuner?

 

[famous bob]

I have never used a dyno of any kind. I go by time slips. Sure there may be more to tuning than time slips but its tough to say something does not work when the ET gets lower and the MPH goes up on the time slips. That's not to say that what you are saying is not true, I'd say my combos are likely not as thorough or completely scienced out as what you build. That goes right back to what I said in my previous reply, it may be a crutch but on most home built cars it works. Are you a pro engine builder/tuner?

do pro stockers run them ? lol

 

[Doosterfy]

do pro stockers run them ? lol

As far as I know pro stock drag cars do not. That shows what Yellow Rose is saying. I wish I had all the time and money to get every last ounce of power out my car but I don't. I'm like most hobby guys, I build my own engines and do my best to choose parts that work well together without cashing in my kids college savings to build them. If I can spend less than $20 on a crutch that makes the car faster and sound better I'll do it. Thank you Yellow Rose for the info, the more we know the better off we are.

 

[crackedback]

Anyone that says an X, H or none has no change in a car isn't speaking anything close to the truth. Look at Myron's results with an extra 30-50# under the car.

Every car is different and the exhaust systems are not likely PERFECT for the application. To say that an X or H don't provide a benefit in any circumstance is ignorant.

 

[ir3333]

Lots of good comments and theories.
..for those that got a hp increase how much did you gain?
..how did you test it?

 

[Locomotion]

Anyone that says an X, H or none has no change in a car isn't speaking anything close to the truth. Look at Myron's results with an extra 30-50# under the car.

Every car is different and the exhaust systems are not likely PERFECT for the application. To say that an X or H don't provide a benefit in any circumstance is ignorant.

Thanks for the vote of confidence. The weight was actually at least 60 lbs, but I compensated by removing the weight from elsewhere in the car to maintain my normal race weight. Nonetheless, after having raced it for years while sorting out the jetting and keeping records as detailed as possible, the car was at least .05 faster and possibly up to .10 after a 1-2 # leaner jet change.

True, it wasn't a totally controlled back-to-back test because I don't have the time, money or resources to eliminate all variables. But the results from my test based on good record keeping showed a benefit on my particular combination. If I wasn't sure of it, I wouldn't have went through the trouble of finding weight elsewhere to remove and put up with the extra difficulty of pulling the trans or center section because the exhaust system is in the way. With the restrictive rules we have in Stock, even small gains can be difficult and expensive to find. So I take them where I can within the rules and my budget.

A similar situation exists with other exhaust "tricks". Merge collectors and step headers, - they have helped some cars and not others. Lots of variable there too. One has to make an "educated decision" based on what they learn about the modification in question (from any and all sources), pick through what they "learn" and decide whether or not it may be be worth trying, and then try to eliminate as many variables and one can. Basically "re-tune" the engine to try and optimize it for the change. Very often, for the average racer, good record keeping, knowing your car and it's reaction to weather changes and time slips are the only tools available to compare before & after results.

I'm under the impression that even an engine "optimized" on a dyno may not have the optimum tune-up at the track, under actual operating conditions. Again, lots of variable there with weather, air flow, loads, etc. Bottom line is the time slip or lap times.

 

[yellow rose]

Thanks for the vote of confidence. The weight was actually at least 60 lbs, but I compensated by removing the weight from elsewhere in the car to maintain my normal race weight. Nonetheless, after having raced it for years while sorting out the jetting and keeping records as detailed as possible, the car was at least .05 faster and possibly up to .10 after a 1-2 # leaner jet change.

True, it wasn't a totally controlled back-to-back test because I don't have the time, money or resources to eliminate all variables. But the results from my test based on good record keeping showed a benefit on my particular combination. If I wasn't sure of it, I wouldn't have went through the trouble of finding weight elsewhere to remove and put up with the extra difficulty of pulling the trans or center section because the exhaust system is in the way. With the restrictive rules we have in Stock, even small gains can be difficult and expensive to find. So I take them where I can within the rules and my budget.

A similar situation exists with other exhaust "tricks". Merge collectors and step headers, - they have helped some cars and not others. Lots of variable there too. One has to make an "educated decision" based on what they learn about the modification in question (from any and all sources), pick through what they "learn" and decide whether or not it may be be worth trying, and then try to eliminate as many variables and one can. Basically "re-tune" the engine to try and optimize it for the change. Very often, for the average racer, good record keeping, knowing your car and it's reaction to weather changes and time slips are the only tools available to compare before & after results.

I'm under the impression that even an engine "optimized" on a dyno may not have the optimum tune-up at the track, under actual operating conditions. Again, lots of variable there with weather, air flow, loads, etc. Bottom line is the time slip or lap times.

I never said that an X or H pipe won't make a car faster. What I said was, in all probability, there is an issue somewhere else.

Again, if you have a million dollar research budget, you may find situations where those things help. I know certain mufflers respond to X and H pipes. I don't use those mufflers.

Like I have said before. I have made cars make LESS horsepower to go faster. Limited tire cars often do better if you can kill some torque at the launch or out of a corner. Some leaf spring cars don't like a big hit to get rolling, or, they don't like a hit in the gear change. Ladder bar 4 speed cars are a nightmare in the gear change.

I have no problem if someone goes faster with something I don't like and have tested. Sometimes you have to give some to get some.

I just like to optimize what I can, and not use techniques that reduce power to go faster if I can avoid it.

It costs a bunch to test. Especially oil, fuel and exhaust. Those things seem to be the most expensive, and the most difficult to isolate and test.